Caption: Hip replacement surgery. Image 28 of 30. Surgeon's hands sewing up during hip replacement surgery. A surgical drain (plastic tube) is in place, and the layers of muscles and fat and skin are being sewn back together. The old hip joint was surgically excised and replaced with a new one. This surgery is usually performed in response to arthritis, degeneration of the joints, and restores mobility to people who would otherwise be incapacitated by pain and unable to move freely. For a sequence of images showing the full surgery, see M551/340-369.